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<head><meta charset="utf-8"><title>what should niko look at · t-compiler · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/index.html">t-compiler</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html">what should niko look at</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164622727" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164622727">(May 01 2019 at 13:24)</a>:</h4>
<p><span class="user-mention" data-user-id="116083">@pnkfelix</span> I'm taking some time to dig into things assigned to me at the moment. I am currently looking at</p>
<ul>
<li>april 2018 trait resolution regression <a href="https://github.com/rust-lang/rust/issues/60010" target="_blank" title="https://github.com/rust-lang/rust/issues/60010">#60010</a> </li>
</ul>
<p>but I also have</p>
<ul>
<li>ICE on higher-trait bounds <a href="https://github.com/rust-lang/rust/issues/60218" target="_blank" title="https://github.com/rust-lang/rust/issues/60218">#60218</a>  (maybe fixed by <span class="user-mention" data-user-id="116118">@Matthew Jasper</span>'s PR <a href="https://github.com/rust-lang/rust/issues/60327" target="_blank" title="https://github.com/rust-lang/rust/issues/60327">#60327</a>)</li>
<li>error: internal compiler error: unexpected region in query response: <code>ReScope(Destruction(219))</code> <a href="https://github.com/rust-lang/rust/issues/60127" target="_blank" title="https://github.com/rust-lang/rust/issues/60127">#60127</a>  (needs to be narrowed down, possibly related to <a href="https://github.com/rust-lang/rust/issues/57464" target="_blank" title="https://github.com/rust-lang/rust/issues/57464">#57464</a>, see next)</li>
<li>Nightly rustc crashes with "unexpected region in query response" <a href="https://github.com/rust-lang/rust/issues/57464" target="_blank" title="https://github.com/rust-lang/rust/issues/57464">#57464</a>  (seems like you and <span class="user-mention" data-user-id="116118">@Matthew Jasper</span> have done some digging here and I see this potentially relates to random regions  appearing in closure signatures, it might be good for us to discuss some more)</li>
<li>user type annotations are captured post normalization <a href="https://github.com/rust-lang/rust/issues/54940" target="_blank" title="https://github.com/rust-lang/rust/issues/54940">#54940</a> (to which I've given approximately zero thought, but I should perhaps give more)</li>
</ul>



<a name="164625524"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164625524" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pnkfelix <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164625524">(May 01 2019 at 14:05)</a>:</h4>
<p>So it looks like <span class="user-mention" data-user-id="116118">@Matthew Jasper</span> had a PR to outlaw returning closures holding lifetimes that were too long, and that included a “principled fix” to, I think, the impl Trait issue I mentioned to you</p>



<a name="164625540"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164625540" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pnkfelix <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164625540">(May 01 2019 at 14:05)</a>:</h4>
<p>This is PR <a href="https://github.com/rust-lang/rust/issues/60332" target="_blank" title="https://github.com/rust-lang/rust/issues/60332">#60332</a></p>



<a name="164625599"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164625599" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pnkfelix <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164625599">(May 01 2019 at 14:06)</a>:</h4>
<p>But a crater run led them to abandon the PR</p>



<a name="164625646"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164625646" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pnkfelix <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164625646">(May 01 2019 at 14:06)</a>:</h4>
<p>If you don’t get to it today, I’ll try to look at that crater run results tomorrow; id like to know if we should try teasing out the impl Trait change on its own, if possible</p>



<a name="164625672"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164625672" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> pnkfelix <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164625672">(May 01 2019 at 14:07)</a>:</h4>
<p>(Possibly as a future-compat warning, to sidestep the crater run issues? Not sure.)</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164627290" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164627290">(May 01 2019 at 14:29)</a>:</h4>
<p>OK, I remember that I had a PR (nt sure of its current state) aiming at a similar thing</p>



<a name="164627447"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164627447" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164627447">(May 01 2019 at 14:31)</a>:</h4>
<p>I am thinking of <a href="https://github.com/rust-lang/rust/pull/55988" target="_blank" title="https://github.com/rust-lang/rust/pull/55988">https://github.com/rust-lang/rust/pull/55988</a></p>



<a name="164627449"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164627449" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164627449">(May 01 2019 at 14:31)</a>:</h4>
<p>it may or may not be related :)</p>



<a name="164627701"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164627701" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164627701">(May 01 2019 at 14:34)</a>:</h4>
<p>I wondered what happened to that when I was working on <a href="https://github.com/rust-lang/rust/issues/60332" target="_blank" title="https://github.com/rust-lang/rust/issues/60332">#60332</a>. I'll have a look to see if it provides a viable approach for us.</p>



<a name="164628103"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164628103" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164628103">(May 01 2019 at 14:39)</a>:</h4>
<p>For now i'm going to look some more into <a href="https://github.com/rust-lang/rust/issues/60010" target="_blank" title="https://github.com/rust-lang/rust/issues/60010">#60010</a></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164628116" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164628116">(May 01 2019 at 14:39)</a>:</h4>
<p>I got distracted by needing to rebuild</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164824093" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Alexey Shmalko <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164824093">(May 03 2019 at 19:44)</a>:</h4>
<p>I have a small fix to Canonicalization chapter of rustc-guide that have been waiting for review for quite some time now (<a href="https://github.com/rust-lang/rustc-guide/pull/304" target="_blank" title="https://github.com/rust-lang/rustc-guide/pull/304">#304</a>). It would be nice if you could take a look, as you have authored the chapter.</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164828061" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> eddyb <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164828061">(May 03 2019 at 20:35)</a>:</h4>
<p>In case you're running out of things :P</p>
<p><a href="https://github.com/rust-lang/rust/pull/59288#discussion_r280920078" target="_blank" title="https://github.com/rust-lang/rust/pull/59288#discussion_r280920078">https://github.com/rust-lang/rust/pull/59288#discussion_r280920078</a></p>
<p><a href="https://github.com/rust-lang/rust/pull/60525" target="_blank" title="https://github.com/rust-lang/rust/pull/60525">https://github.com/rust-lang/rust/pull/60525</a></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164842896" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> eddyb <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164842896">(May 04 2019 at 01:14)</a>:</h4>
<p>or if you have opinions on <a href="https://github.com/rust-lang/rust/pull/60530" target="_blank" title="https://github.com/rust-lang/rust/pull/60530">https://github.com/rust-lang/rust/pull/60530</a></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/what%20should%20niko%20look%20at/near/164983324" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> eddyb <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/what.20should.20niko.20look.20at.html#164983324">(May 06 2019 at 13:55)</a>:</h4>
<p>this one is not one of mine, but they are asking for you <a href="https://github.com/rust-lang/rust/pull/49799#issuecomment-489493241" target="_blank" title="https://github.com/rust-lang/rust/pull/49799#issuecomment-489493241">https://github.com/rust-lang/rust/pull/49799#issuecomment-489493241</a></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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